Clavicle

Contents

Name of bone

Clavicle

Location/Articulation

The clavicle is a doubly curved short bone that connects the arm (upper limb) to the body (trunk). It is located directly above the first rib, and it acts as a strut to keep the scapula in position so the arm can hang freely. Medially, it articulates with the manubrium of the sternum (breast-bone) at the sternoclavicular joint. At its lateral end it articulates with the acromion of the scapula (shoulder blade) at the acromioclavicular joint. It has a rounded medial end and a flattened lateral end.

From the roughly pyramidal sternal end, each clavicle curves laterally and posteriorly for roughly half its length. It then forms a smooth posterior curve to articulate with a process of the scapula (acromion). The flat, acromial end of the clavicle is broader than the sternal end. The acromial end has a rough inferior surface that bears prominent lines and tubercles. These surface features are attachment sites for muscles and ligaments of the shoulder.

Muscle and ligament attachments

Muscles and ligaments that attach to the clavicle include the following:

Attachment on clavicle	Muscle/Ligament	Other attachment
Superior surface and anterior border	Deltoid muscle	Deltoid tubercle, anteriorly on the lateral third
Superior surface	Trapezius muscle	Posteriorly on the lateral third
Inferior surface	Subclavius muscle	Subclavian groove
Inferior surface	Conoid ligament (the medial part of the coracoclavicular ligament)	Conoid tubercle
Inferior surface	Trapezoid ligament (the lateral part of the coracoclavicular ligament)	Trapezoid line
Anterior border	Pectoralis major muscle	medial third (rounded border)
Posterior border	Sternocleidomastoid muscle (clavicular head)	Superiorly, on the medial third
Posterior border	Sternohyoid muscle	Inferiorly, on the medial third
Posterior border	Trapezius muscle	Lateral third

Surface anatomy

Clavicle fractures are extremely common. Broken collarbones occur in babies (usually during birth), children and adolescents (because the clavicle does not completely ossify, or develop, until the late teens), and athletes (because of the risks of being hit or falling) and during many types of accidents and falls.

Radiography

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Physical examination

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Embryology

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Anomalies

The clavicle varies more in shape than most other long bones. Occasionally, the clavicle is pierced by a branch of the supraclavicular nerve. The clavicle is thicker and more curved in manual workers, and the sites of muscular attachments are more marked. The right clavicle is usually stronger and shorter than the left clavicle.

Injuries/Disorders

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Figures

Figure 1. Clavicle